This invention relates to in-process monitoring of welding conditions from which weld quality evaluations are automatically made and utilized to eject defective articles in production.
The sensing of electrical conditions and evaluation of associated parameters for determining the quality or integrity of welds is generally known as disclosed for example in U.S. Pat. No. 3,582,967 to Beckman owned by the assignee of the present application. According to the Beckman patent, the total energy delivered to a spot weld during a welding cycle through a standard welding machine is monitored by measurement of the input voltage across the welding electrodes. However, there are no heretofore known standards for the electrical conditions that occur during a welding operation to produce a weld of acceptable quality. In particular, there were no such standards available for in-process determination of quality for the spot welds formed along the seam of a can being welded by rotating electrode wheels during movement of the can along a conveyor path of a production line, so that cans with defective welds could be ejected at some location downstream of the welding station.
It is therefore an important object of the present invention to provide a method and apparatus for monitoring more meaningful conditions and evaluating measurements of such conditions during a welding operation for making rapid and accurate judgements as to weld quality.
Another object in combination with the foregoing object is to provide a method and means for utilizing the weld quality judgements to control ejection of articles with defective welds from the production line and interrupt the supply of welding energy to prevent equipment damage.